Carburetor system for combustion engines

ABSTRACT

A carburetor system for combustion engines having a relatively long intake duct is provided with a rating system which is arranged separate from the main nozzle system. This idling system is located near the intake of the combustion engine. Under these circumstances, the formation of the idling mixture takes place before its introduction into the engine intake so that there is no possibility of mixture separation. In one proposed embodiment, a check valve is provided for preventing backflow of fuel or fuel-air mixture to affect the idler. In another embodiment, the idling system together with the throttling flap is arranged in a flange interposed between the engine and intake duct. The air nozzle of this idling system is connected to the intake duct by a passage located upstream from the throttling flap. In a further embodiment, the idling system is arranged in the engine housing or the cylinder head itself. In this regard, the idling system is connected to the inlet passage by a line thereby providing for a short route for the idling mixture to the intake chamber of the combustion engine.

United States Patent Gerd Reinhardt Adelsheim;

Horst Heide. Odheim; Sebastian Flinspach, Binswangen, all of Germany Oct. 21 1969 Nov. 16, 197 1 Audi NSU Auto Union Aktiengesellschaft Neckarsulm, Germany [32] Priority Oct. 22, 1968 [33] Germany [72] Inventors [21 App]. No. [22] Filed [45] Patented 73] Assignee [54] CARBURETOR SYSTEM FOR COMBUSTION 3,006.327 10/1961 Holley. Jr. et a1 12 11) 3.188.062 6/1965 Reid etal 261 41 D 3.283.751 11/1966 Goossak etaln 121 119 3.382.856 5/1968 Mcllroynm. 123/ll9X 3475.011 10/1969 Cook 123119X Primary Examiner-Tim R. Miles Al!0rm'\-Kane. Dalsimer. Kane. Sullivan and Kuruez ABSTRACT: A carburetor system for combustion engines having a relatively long intake duct is provided with a rating system which is arranged separate from the main nozzle system. This idling system is located near the intake of the combustion engine Under these circumstances. the formation of the idling mixture takes place before its introduction into the engine intake so that there is no possibility of mixture separation In one proposed embodiment, a check valve is provided for preventing backflow of fuel or fuel-air mixture to affect the idler. In another embodiment. the idling system together with the throttling flap is arranged in a flange interposed between the engine and intake duct. The air nozzle of this idling system is connected to the intake duct by a passage located upstream from the throttling flapl In a further embodiment, the idling system is arranged in the engine housing or the cylinder head itself. 1n this regard. the idling system is connected to the inlet passage by a line thereby providing for a short route for the idling mixture to the intake chamber of the combustion engine.

PATENTEUNnv 16 ml 3,620.51 1

SHEEI 1 [IF 2 @Jmli. M 0

ATTORNEYS PA'TENTEUNUV 1e IQTI 3520,51 1

sum 2 or 2 A at;

F/GZ

/ N Vf/Y TOPS BY 5, 3M, 4. W 7

ATTORNEYS CARBURETOR SYSTEM FOR COMBUSTION ENGINES BACKGROUND OF THE INVENTION The invention relates to a carburetor system for combustion engines having a long intake duct, in particular rotary-piston combustion engines, comprising a main nozzle system (partial and full load) and an idling system as well as a throttling flap arranged in the intake duct.

In combustion engines with long intake duct, considerable trouble arises in idling because the long ducts favor precipitation of fuel droplets at the comparatively low flow velocities in this operating condition, with resulting uneven idling. At tempts have been made to remedy this disadvantage by providing a special idling inlet passage, of correspondingly smaller cross section, opening into the intake duct or inlet passage as close to the intake chamber as possible. The smaller passage cross section and the resulting higher flow velocity did in fact improve the situation, but still, on the comparatively long route from the idling system of the carburetor to the opening of the idling inlet passage into the intake duct, some partial separation might occur after all.

The object of the invention is to avoid these disadvantages and provide a carburetor system in which separation of the idling mixture practically cannot occur. This problem is solved, according to the invention, in that the idling system (idling fuel nozzle, idling air nozzle, idling mixture adjustment screw) is arranged separate from the main system, at a slight distance ahead of the opening of the idling mixture line into the intake duct or inlet passage, near the intake chamber. By virtue of the proposal according to the invention, the formation of the idling mixture takes place only just before introduction into the intake duct or inlet passage, so that there is no possibility of mixture separation. This ensures stable, uniform idling.

The idling system is preferably arranged in a flange between engine and intake duct, simplifying manufacture and assembly. It is expedient in that case to arrange the throttling flap in the flange as well, since it is thus possible by simple means to connect the air nozzle of the idling system by way of a passage to the intake duct at a point upstream from the throttling flap, so that filtered air is supplied to the idling system.

The idling system may alternatively be arranged in the engine housingor the cylinder head itself and connected to the inlet passage by a line. This results in especially short routes from the mouth of the idling mixture line to the intake chamber of the combustion engine.

The fuel nozzle of the idling system is preferably connected to the float chamber of the main nozzle system.

It is especially expedient to provide an independent idling passage with which the idling system is in communication.

While the arrangement of the idling system near the engine inlet avoids separation of the idling mixture, nevertheless, in this region of the intake duct or inlet passage near the engine inlet, especially in the case of slit-controlled engines, intense pulsations occur, with the result that the fuel or fuel-air mixture is forced back, whereby the idler is affected in an unpredictable manner. To eliminate this disadvantage, it is proposed, according to the invention, that a check valve opening in the direction of flow be provided in the idling fuel line or idling mixture line. This check valve is opened by the suction in the intake duct, so that idling mixture can enter the engine in the normal way. But when a compression wave builds up in the intake duct owing to pulsation,'the check valve will be closed by the pressure, and any spurting of fuel out of the air correction nozzle of the main system or forcing back of fuel into the float chamber will be reliably prevented.

An embodiment of the invention by way of example will now be described with reference to the drawings, in which:

F l0. 1 shows a top view of a flange to be arranged between engine and intake duct with idling system according to the invention, in partial section; and

FIG. 2 shows a section at the line A-A in FIG. 1, part of the engine and carburetor with main nozzle system being represented schematically.

in the illustrated embodiment, a flange 3 arranged between engine 1 and intake duct 2 has two main inlet passages 4, each with a throttling flap 5. Each main inlet passage 4 is associated with an idling inlet passage 6. Both passages 4 and 6 open into the engine inlet passage 7. At a point upstream from the throttling flap 5, an idling air passage 8 extends from one of the main inlet passages 4 to a chamber 9. Passage 8 is calibrated in its final segment 8a, and serves at the same time as an idling air nozzle. lnto chamber 9 opens a fuel line 10 in which the fuel nozzle 11 is arranged ahead of chamber 9. The fuel line 10 is closable by a check valve 12, (a leaf spring valve in the embodiment of the example, but in principle of any type). From chamber 9, an idling mixture line 13 extends by way of an idling mixture adjusting screw 14 to each of the idling inlet passages 6. Into each of the idling inlet passages 6 there opens also a passage 15 for supplementary air, proceeding from the respective main inlet passage 4 upstream from the throttling flap 5, with an air-adjusting screw 16 arranged in each.

The fuel line 10 of the idling system is in communication with the float chamber 17 of the main system. In principle, however, an independent level control reservoir might equally be provided to feed the idling system.

The check valve 12 serves the purpose of preventing the fuel from being forced back into the float housing 17 or main nozzle system in case of pulsations in the idling inlet passage 6. Of course, this check valve might alternatively be arranged in the idling mixture line 13.

Although a preferred embodiment of this invention has been described and illustrated herein, it should be understood that this invention is in no sense limited thereby but its scope is to be determined by that of the appended claims.

We claim:

1. In a carburetor system for combustion engines of the rotary piston engine type, comprising a carburetor having a main nozzle system and an idling system, the carburetor being connected to the inlet passage of the combustion engine and communicating with the intake chamber thereof by a relatively long intake duct having an upstream and downstream end, the idling system including fuel-air mixing means being arranged adjacent the downstream end of the intake duct :1 short distance ahead of the opening of the idling mixture line into the inlet passage close to the intake chamber of the engine so that idling fuel is mixed with idling air at a short distance from the inlet passage thereby minimizing air-fuel mixture separation in the idling system and accordingly assure uniform idling.

2. Carburetor system according to claim 1 wherein the idling system is arranged in a flange between the engine and intake duct.

3. Carburetor system according to claim I wherein a throttling flap is arranged in the intake duct.

4. Carburetor system according to claim 3 wherein the throttling flap is arranged in a flange between the engine and intake duct.

5. Carburetor system according to claim 3 wherein the air nozzle of the idling system communicates by a passage with the intake duct at a point upstream of the throttling flap.

6. Carburetor system according to claim 1 wherein the fuel nozzle of the idling system is connected to the float chamber of the main nozzle system.

7. Carburetor system according to claim 1 wherein an independent idling inlet passage is provided with which the idling system is in communication.

8. Carburetor system according to claim I wherein a check valve opening in the direction of flow is provided in one of the idling lines. 

1. In a carburetor system for combustion engines of the rotary piston engine type, comprising a carburetor having a main nozzle system and an idling system, the carburetor being connected to the inlet passage of the combustion engine and communicating with the intake chamber thereof by a relatively long intake duct having an upstream and downstream end, the idling system including fuel-air mixing means being arranged adjacent the downstream end of the intake duct a short distance ahead of the opening of the idling mixture line into the inlet passage close to the intake chamber of the engine so that idling fuel is mixed with idling air at a short distance from the inlet passage thereby minimizing air-fuel mixture separation in the idling system and accordingly assure uniform idling.
 2. Carburetor system according to claim 1 wherein the idling system is arranged in a flange between the engine and intake duct.
 3. Carburetor system according to claim 1 wherein a throttling flap is arranged in the intake duct.
 4. Carburetor system according to claim 3 wherein the throttling flap is arranged in a flange between the engine and intake duct.
 5. Carburetor system according to claim 3 wherein the air nozzle of the idling system communicates by a passage with the intake duct at a point upstream of the throttling flap.
 6. Carburetor system according to claim 1 wherein the fuel nozzle of the idling system is connected to the float chamber of the main nozzle system.
 7. Carburetor system according to claim 1 wherein an independent idling inlet passage is provided with which the idling system is in communication.
 8. Carburetor system according to claim 1 wherein a check valve opening in the direction of flow is provided in one of the idling lines. 